Tamarindus indica, a beneficial herb, has many health benefits but there is limited research on its use in fish nutrition industry. The current study investigated the effects of incorporating extracts of T. indica into the canola meal-based diets of Cyprinus carpio (common carp); following which, the growth, digestibility, carcass and hematological markers were assessed. A total of six diets were formulated with varying concentrations of T. indica extracts (TIE) viz, 0 %, 0.5 %, 1 %, 1.5 %, 2 % and 2.5 %. The fish (N = 270, 15 fish/tank with triplicates) in each tank were fed experimental diets for 70 days. The study demonstrated that TIE supplementation significantly improved the growth of common carp when compared to 0 % TIE level (control). The best results were observed at 1 % TIE level for the specific growth rate (1.68 ± 0.03 %), weight gain (15.00 ± 0.57 g), and feed conversion ratio (1.36 ± 0.05). Conversely, the 2.5 % TIE level gave the least improvement in terms of growth performance. Specifically for nutrient digestibility, the maximum values of crude protein (CP, 67.60 ± 0.83 %), crude fat (CF, 67.49 ± 0.45 %) and gross energy (GE, 70.90 ± 0.56 %) were recorded at 1 % TIE level. In addition, the best results of body composition (protein: 63.92 ± 0.06 %, ash: 18.60 ± 0.03 %, fat: 7.12 ± 0.02 % and moisture: 10.36 ± 0.04 %) and hematological indices, were measured in carps fed with 1 % supplementation level. In conclusion, the overall health of C. carpio fingerlings was improved with TIE supplementation in the diet containing 1 % TIE.

In this study, we investigated the growth dynamics and otolith shape asymmetry of two fish species, Chrysichthys nigrodigitatus (CN) and Oreochromis niloticus (ON), within urbanized watersheds of the southern lagoon system, Nigeria. Using the von Bertalanffy growth model (VBGM), in addition to sediment metal concentration indices such as the average shale content, index of geoaccumulation (Igeo), contamination factor (CF), pollution load index (PLI), and potential ecological risk (PER) index, contamination levels were classified, and ecological risks were assessed. Notably, a lower growth potential (t0) was observed in CN at Ikorodu than at Epe, with similar trends for ON in the Epe during the dry season. Otolith asymmetry patterns, particularly in the CN at Ikorodu and ON in the Epe during the dry season, exhibited distinct ecological variations, indicating heightened stress levels at Ikorodu. Sediment analyses revealed moderate to strong contamination (Cd, Pb, Ni, and Cr) in both Lagos Lagoon (Ikorodu) and Epe Lagoon, with Ikorodu exhibiting notably high to moderate contamination levels according to the CF index. Elevated PLI values for Cd and Pb in Ikorodu, in addition to greater PER, indicated increased risk, with Cd posing a high risk (61.42%) and Pb posing a moderate risk (49.50%). Additionally, the reduced asymptotic length in the Epe during the dry season suggests that Chrysichthys nigrodigitatus is adaptable to seasonal variations, while divergent growth patterns in both areas indicate the existence of trade-off mechanisms in response to changing conditions. Habitat-specific otolith asymmetry and metal contamination underscore species adaptability, with wider stressor variability in Lagos than in Epe. Furthermore, multidimensional scaling analysis highlights the intricate relationship between otolith shape variables and environmental factors, emphasizing the need for tailored conservation efforts in urbanized watersheds.

Understanding individual growth in commercially exploited fish populations is key to successful stock assessment and informed ecosystem-based fisheries management. Traditionally, growth rates in marine fish are estimated using otolith age-readings in combination with age-length relationships from field samples, or tag-recapture field experiments. However, for some species, otolith-based approaches have been proven unreliable and tag-recapture experiments suffer from high working effort and costs as well as low recapture rates. An important alternative approach for estimating fish growth is represented by bioenergetic modelling which in addition to pure growth estimation can provide valuable insights into the processes leading to temporal growth changes resulting from environmental and related behavioural changes. We here developed an individual-based bioenergetic model for Western Baltic cod (Gadus morhua), traditionally a commercially important fish species that however collapsed recently and likely suffers from climate change effects. Western Baltic cod is an ideal case study for bioenergetic modelling because of recently gained in-situ process knowledge on spatial distribution and feeding behaviour based on highly resolved data on stomachs and fish distribution. Additionally, physiological processes such as gastric evacuation, consumption, net-conversion efficiency and metabolic rates have been well studied for cod in laboratory experiments. Our model reliably reproduced seasonal growth patterns observed in the field. Importantly, our bioenergetic modelling approach implementing depth-use patterns and food intake allowed us to explain the potentially detrimental effect summer heat periods have on the growth of Western Baltic cod that likely will increasingly occur in the future. Hence, our model simulations highlighted a potential mechanism on how warming due to climate change affects the growth of a key species that may apply for similar environments elsewhere.

The Lower Duwamish River is a highly industrialized waterway flowing into the densely urbanized Puget Sound waterfront of Seattle, Washington, USA. The river has been profoundly altered from its natural state following more than a century of channelization, recurrent dredging, shoreline armoring, and pollution discharges. As part of a Natural Resource Damage Assessment addressing historical pollution at three designated Superfund sites (i.e., the assessment area), juvenile Pacific staghorn sculpin (Leptocottus armatus) were sampled throughout the lower river in order to evaluate injury from exposure to polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDTs), and butyltins (BTs). Sculpin live in close association with the river sediments within and upriver of the assessment area. Fish were collected for analysis of contaminant concentrations in composited whole bodies and stomach contents, as well as individual fish health metrics including daily somatic growth rates measured from otoliths. Sediment contaminant concentrations were also measured at sites near to fishing locations. Fish growth rates varied from 0.65 to 1.05 mm/day, and were significantly lower at unremediated downriver sites compared to upriver and remediated locations. Sculpin growth rates were negatively correlated with concentrations of PCBs in fish bodies, PAHs in stomach contents, as well as PCBs, DDTs and PAHs in sediment. Mixed effects models for whole-body and stomach content contaminants showed positive correlations between growth rate and water temperature. Temperature was not a significant confounding variable for the relationship between growth rate and sediment contaminants. Overall, these results show that juvenile sculpin are harmed by contaminant exposure in the Lower Duwamish River. Furthermore, this study demonstrates the utility of using paired biological and chemical indicators of pollutant-induced injury in a resident fish to inform a complex Natural Resource Damage Assessment and associated restoration efforts.

The study aimed to investigate the effect of Cu exposure (0, 51.3, 164, 513, 1,640, and 5,130 μg/L) on fish growth performance, histology, oxidative stress, inflammation, and apoptosis in largemouth bass (Micropterus salmoides) juveniles. 270 fish (2.69 ± 0.02 g) were randomly divided into 6 groups of tanks for 4 weeks with each group comprising three replicate tanks. The results showed that fish exposed to 1,640 and 5,130 μg/L Cu exhibited a significant reduction in fish growth and survival rate (P < 0.05). Compared to the control, the fish at and above 513 μg/L Cu demonstrated histopathological damages in the gills and liver, such as shorter primary and secondary lamellae, smaller hepatocyte nuclei, and an increase in the number of necrotic cells in the liver. Compared to the control, fish at and above 1,640 μg/L Cu had a significantly higher malondialdehyde content and lower activity levels of total superoxide dismutase, glutathione peroxidase, and catalase in the gills and liver (P < 0.05). Furthermore, high concentrations of Cu (1,640 and 5,130 μg/L) significantly increased hepatic inflammation by upregulating interleukin-1β and tumor necrosis factor α expression and hepatic apoptosis by increasing cysteinyl aspartate specific protease 3 (caspase-3) and caspase-9 expression (P < 0.05). Pearson correlation analysis showed that fish growth and survival positively correlated with histological and antioxidant defense parameters, and negatively correlated with oxidative stress parameters, hepatic inflammation, and hepatic apoptosis. Taken together, these results suggest that high levels of waterborne Cu can induce growth retardation and mortality by damaging the liver and gill health.

Global warming is leading to an increase in the frequency and intensity of extreme weather events, magnifying the breadth of temperatures faced by ectotherms across days and seasons. Despite the importance and ecological relevance of diurnal thermal variability, the vast majority of knowledge on gene expression patterns and physiology stems from animals acclimated to constant temperatures or in the early stages of exposure to a new temperature regime. If heterothermal environments modulate responses differently from constant thermal environments, our existing capacity to forecast impacts of climate warming may be compromised. To address this knowledge gap, we acclimated barramundi (Lates calcarifer) to 23 °C, 29 °C (optimal), 35 °C and to thermal cycling conditions (23-35 °C daily with a mean of 29 °C) and sampled liver and white muscle tissue before acclimation and after 2 and 17 weeks of acclimation. NanoString nCounter technologies were used to measure expression of 20 genes related to metabolism, growth and maintenance of cellular homeostasis. Acclimation to cool and warm conditions caused predictable changes in whole-animal performance (metabolism and growth) and the underlying gene expression patterns. Acclimation to a cycling temperature regime did not change the molecular regulation of metabolism or growth compared with barramundi acclimated to constant 29 °C, nor did it cause any discernible effects on whole-animal performance. However, the heat shock response was higher in the former group, suggesting that barramundi under a daily temperature cycle have an increased need for cellular chaperoning to minimise detrimental effects of temperature on proteins. We conclude that the genetic regulation of metabolism and growth may be more dependent on the mean daily temperature than on the daily temperature range.

Climate-driven changes including rising air temperatures, enhanced permafrost degradation, and altered precipitation patterns can have profound effects on contaminants, such as mercury (Hg), in High Arctic lakes. Two physically similar lakes, East Lake and West Lake at the Cape Bounty Arctic Watershed Observatory on Melville Island, Nunavut, Canada are being affected by climate change differently. Both lakes have experienced permafrost degradation in their catchments; however, West Lake has also undergone multiple underwater Mass Movement Events (MMEs; beginning in fall 2008), leading to a sustained 50-fold increase in turbidity. This provided the unique opportunity to understand the potential impacts of permafrost degradation and other climate-related effects on Hg concentrations and body condition of landlocked Arctic char (Salvelinus alpinus), an important sentinel species across the Circum-Arctic. Our objectives were to assess temporal trends in char Hg concentrations and to determine potential mechanisms driving the trends. There was a significant decrease in Hg concentrations in East Lake char, averaging 6.5%/year and 3.8%/year for length-adjusted and age-adjusted means, respectively, from 2008 to 2019. Conversely, in West Lake there was a significant increase, averaging 7.9%/year and 8.0%/year for length-adjusted and age-adjusted mean Hg concentrations, respectively, for 2009 to 2017 (the last year with sufficient sample size). The best predictors of length-adjusted Hg concentrations in West Lake were carbon and nitrogen stable isotope ratios, indicating a shift in diet including possible dietary starvation brought on by the profound increase in lake turbidity. Our study provides an example of how increasing lake turbidity, a likely consequence of climate warming in Arctic lakes, may influence fish condition and Hg concentrations. Environ Toxicol Chem 2023;42:2712-2725. © 2023 His Majesty the King in Right of Canada and The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

Chicken feather meal has had a significant biofertilizer approach in recent years. The current study aims to assess feather biodegradation to promote plant and fish growth. The Geobacillus thermodenitrificans PS41 strain was more efficient in feather degradation. Feather residues were separated after degradation and evaluated under a scanning electron microscope (SEM) to detect bacterial colonization on feather degradation. It was observed that the rachi and barbules were entirely degraded. The complete degradation by PS41 suggests a relatively more efficient feather degradation strain. According to Fourier-transform infrared spectroscopy (FT-IR) studies, PS41 biodegraded feathers contain the functional groups of aromatic, amine, and nitro compounds. The present study suggested that biologically degraded feather meal improved plant growth. The feather meal combined with nitrogen-fixing bacterial strain showed the highest efficiency. The biologically degraded feather meal and Rhizobium combination induced physical and chemical changes in the soil. It is directly involved in soil amelioration, plant growth substance, and soil fertility, enhancing a healthy crop environment. The feather meal 4 and 5% was used as a feed diet of common carp (Cyprinus carpio) to increase growth performances and feed utilization parameters. In hematological and histological studies of formulated diets, significantly no toxic effects occurred in fish blood, gut, or fimbriae.

The study aimed to evaluate the effects of phosphorus (P) deficiency in diets on growth performance, hepatic lipid metabolism, and antioxidant capacity in Yellow River Carp Cyprinus carpio haematopterus.
In this study, 72 healthy experimental fish (initial weight = 12.0 ± 0.1 g [mean ± SE]) were randomly selected and distributed to two groups, with three replicates in each group. The groups were fed either a P-sufficient diet or a P-deficient diet for 8 weeks.
The P-deficient feed significantly decreased the specific growth rate, feed efficiency, and condition factor of Yellow River Carp. Fish that were fed the P-deficient feed demonstrated higher contents of triglyceride, total cholesterol (T-CHO), and low-density lipoprotein cholesterol in the plasma and a higher T-CHO content in the liver compared to the P-sufficient diet group. In addition, the P-deficient diet significantly reduced the catalase activity level, decreased the glutathione content, and increased the malondialdehyde content in the liver and in the plasma. Furthermore, P deficiency in the diet significantly downregulated the messenger RNA expression of nuclear erythroid 2-related factor 2 and peroxisome proliferator-activated receptor α, whereas it upregulated the messenger RNA expression of tumor necrosis factor α and fatty acid synthase in the liver.
Dietary P deficiency reduced fish growth performance, induced fat deposition and oxidative stress, and impaired liver health.

The aim of the present work was to investigate the influence of fasting and refeeding on body condition, gut physiology and microbiota in reared O. mykiss. Ninety-six fish were randomly allotted among three groups subjected to different feeding plan: C (control, fed for 5 weeks); R (restricted ration over 3 weeks followed by 2 weeks feeding); F (fasted over 3 weeks followed by 2 weeks feeding) in a well\'s fresh water flow-through rearing plan. Sampling occurred at 0, 1, 2, 4, 7, 14 days during the refeeding period. At day 0 and throughout the feeding period until day 14, the weight of the fish was significantly affected by the feeding restriction. Feed deprivation reduced significantly the viscerosomatic and hepatosomatic indexes. Brush border membrane enzymes\' specific activity was modulated by feeding regimes until day 7, to level in all experimental groups at day 14. At the end of the restricted/fasted period, the microbiota of the C group was made up of 70% of Actinobacteria, 24% of Proteobacteria, 4.2% of Firmicutes and < 1% of Bacteroides, while the restricted and fasted group were characterized by a strong reduction of Actinobacteria, and a significant increase in Bacteroidetes and Firmicutes. The feed deprivation determined a dysbiosis, allowing the development of different commensal or pathogenic bacteria. In conclusion, the effects of 2 weeks of feed deprivation, excluding those related to body weight, are gradually mitigated by refeeding, which allows the restoration of digestive functions and a healthy intestinal microbiota.